Technical Abstract:
Berry rot diseases reduce yield and quality of muscadine grapes, but those losses may be minimized by fungicide applications. The fungicides, myclobutanil, azoxystrobin, and tebuconazole, were applied sequentially to two muscadine cultivars every ten days beginning at early bloom and stopping at pre-harvest intervals (PHIs) of 64, 42, 28, 14, 7, 4, 2, 1, and 0 days. Objectives were to determine spray schedule effects on foliage and berry diseases and the relationship between disease incidence and berry resveratrol content. Resveratrol, a phytoalexin, has shown potential for prevention and treatment of cardiovascular disease and certain types of cancer. Resveratrol content in berry skins was determined by HPLC. Foliar and berry diseases were rated visually at harvest. All fungal diseases were lower on `Doreen' than on `Summit' and were reduced by fungicide treatments. There were no differences in the number of asymptomatic berries among the 9 PHIs. Resveratrol content of berry skins from fungicide treated vines was significantly lower than those from untreated vines.